In manufacturing steps of a semiconductor device, there is a possibility that particles adhere to a surface of a semiconductor wafer (hereinafter also referred to simply as “wafer”), during a film-deposition process and an etching process for the wafer, for example. Thus, it is necessary to clean the surface of the wafer.
As a wafer cleaning apparatus for cleaning a wafer, there has been known an apparatus that cleans a wafer, by supplying a cleaning liquid of a deionized water or a chemical liquid onto a surface of the wafer which is being rotated by a spin chuck, then rinsing the wafer, and finally rotating the wafer at a high speed to dry the same.
There is a case in which a cleaning liquid containing hydrofluoro ether (hereinafter also referred to simply as “HFE”) is used as a cleaning liquid to be supplied to the wafer (see, IP2005-5469A, IP2006-41065A, and JP2002-124504A). As compared with a conventional cleaning liquid of, e.g., a deionized water, a surface tension and a viscosity of the cleaning liquid containing HFE are significantly lowered. Thus, the cleaning liquid containing HFE is capable of easily entering small recesses in a surface of a wafer, so that a slight amount of particles resting in the small recesses can be favorably removed. Further, a specific gravity of HFE is about 1.5, which is greater than a specific gravity of water. Thus, when HFE is supplied onto a surface of a wafer, the HFE collides with the wafer with a greater kinetic energy. As a result, a processing efficiency of the wafer can be enhanced. Furthermore, since HFE does not have a flash point, there is no possibility that HFE catches fire during a process of the wafer.